What is Base64?
Base64 is a binary-to-text encoding scheme that represents arbitrary binary data using 64 printable ASCII characters (A–Z, a–z, 0–9, + and /). It is used to safely embed or transmit binary data — like images or files — through systems that only handle text, such as JSON, email (MIME), and data URIs.
Base64 is encoding, not encryption: anyone can decode it instantly, so it provides no security. Encoded output is about 33% larger than the original data.
Key points
- Every 3 bytes of input become 4 Base64 characters, so the output is ~33% larger.
- The alphabet is A–Z, a–z, 0–9, + and /, with = used for padding.
- It is fully reversible by anyone — Base64 is encoding, not encryption.
- Base64URL is a variant that swaps + and / for - and _ so the result is URL-safe.
Example
Text: Hi! Base64: SGkh
Common uses
- Embedding small images or fonts directly in CSS/HTML as data URIs
- Encoding binary attachments in email (MIME)
- Carrying binary data inside JSON or XML payloads
- The three segments of a JWT are Base64URL-encoded
Work with Base64 directly in your browser.
Open the Base64 Encoder/Decoder